1. Background
Embodiments described relate to dry resin sorbent systems in a by-pass line of a semiconductor process tool useful for reducing toxic and/or hazardous gaseous components deriving therefrom.
2. Background of the Related Art
Typical and emerging semiconductor Epitaxial (EPI) processes use toxic and/or hazardous source gases such as arsine (AsH3), phosphine (PH3), germane (GeH4) and diborane (B2H6) for deposition of hetero-epitaxial thin films. Many of these processes are equipped with point-of use (POU) water scrubbers, which are designed to abate specific gases used in such processes, such as dichlorosilane (SiH2Cl2). However, wet scrubbers are ineffective at abating many hydride gases such as AsH3 and PH3. If a point-of-use water scrubber is used, the unabated hydride gases may be released to the roof, where they can be further re-entrained into the semiconductor facility through make up air fans.
These toxic and/or hazardous gases are typically diluted with hydrogen when fed to EPI reactors, many of which continuously by-pass some of that gas to “equalize” pressure/flow to the reactor. By such design, during deposition, only a small amount of hydride gas flows to the reactor, while a much larger amount bypasses the chamber and goes directly to vent. The by-pass can go to outside air directly or to a POU abatement system on the EPI reactor.
Many EPI processes feed hydride gases in ppm levels and mass flow controllers are typically used to control their flow. The hydride gas may be used in combination with diluents and/or are combined therewith in a mixing manifold up-stream of a mass-flow controller. Pressure in the manifold is maintained at a constant level by pressure controllers, transducers etc.
It is plausible to use a thermal oxidizer in the bypass line to reduce the occurrence of hydride gas components being released to the environment or ventilation system. However, if the hydride gas component in the bypass line is, for example, arsine, arsenic-containing waste is generated, which must be handled and treated carefully as arsenic is highly toxic. Further, a high cost of ownership is associated with thermal oxidizers, particularly in the area of fuel consumption.
Alternatively a combination thermal/wet scrubber may be used in the bypass line to reduce the occurrence of hydride gas components being released to the environment or ventilation system. However, if arsenic is present in the by-pass line, arsenic-containing by-products will become entrained in the wastewater. The arsenic-contaminated water is highly controlled in certain areas of the United States and will likely require further treatment prior to disposal. Moreover, initial costs of such a system start in a six-digit dollar range and maintenance and operational costs are predicted to start in a five-digit dollar range.
Therefore, it is one objective of the present invention, to provide an inexpensive solution to controlling the release of hazardous and/or toxic gas components from a bypass line upstream of a semiconductor process tool.
It is a further objective of the present invention to provide an inexpensive solution to controlling the release of hazardous and/or toxic gas components from a point-of-use water scrubber.